Events leading to the destruction of articular cartilage from injection are being investigated. Bacteria which commonly cause joint infection in people are being investigated, both in vitro and in vivo. Elaboration by the bacteria of enzymes destructive for constituents of cartilage are evaluated. In addition, the reaction that bacteria or bacterial cell products create in the synovium of rabbit knee joints is an integral part of the studies. Bacteria or bacterial cell products are directly innoculated into rabbit knee joints or into tissue culture and the pathology over time observed. Using a model of rabbit knee joints directly infected with bacteria, principles of treatment as they might apply to patients are studied. The number of bacteria required to produce infection under such circumstances is utilized as a dose response curve. These studies particularly concern themselves with the use of antibiotics. Complementary pharmacologic studies are carried out to correlate tissue antibiotic levels in the efficacy and timing of various regimens. BIBLIOGRAPHIC REFERENCE: D.J. Schurman, J. Kajiyama, K. Moser, D. Nagel: "Antimicrobial Studies of E. coli Joint Infections: A Study of Synergism in a Rabbit Model." Transactions of the Orthopedic Research Society, 23rd Annual Meeting, Las Vegas, Nevada, 2, 73, 1977.